Japan Maritime Self-Defense Force's P-3C Orion surveillance plane flies over disputed islands in the East China Sea, called the Senkaku in Japan and Diaoyu in China, in 2011. (Kyodo News / via AP)

WASHINGTON — Japan’s ambassador called for improved relations with China on Wednesday as the top U.S. intelligence official warned that territorial disputes and nationalist fervor are increasing the risk of conflict in East Asia.

Ambassador Kenichiro Sasae said people are afraid of the consequences of a deteriorating relationship between the two Asian powers, and appealed for a calming of “agitated remarks” from both sides.

Sasae told a Washington think tank that constructive dialogue was needed but also said Japan would not give in to pressure over its sovereignty claims.

The long-running dispute over unoccupied islands that Japan calls Senkaku and China calls Diaoyu has grown more intense since Japan, a key U.S. ally, nationalized some of them in 2012. China has stepped up patrols around the islands, which are controlled by Japan but claimed by both nations. China recently declared an air defense zone over the islands, drawing stiff international criticism.

U.S. Director of National Intelligence James Clapper told a Senate Intelligence Committee hearing on worldwide threats Wednesday that China will probably continue a “hard-line stance” toward Japan over the islands.

In written testimony that also noted China’s military modernization and growing confidence, Clapper predicted that sovereignty concerns and historical resentments will generate friction and “occasional incidents” between claimants in the East and South China Sea.

China has competing territorial claims with several neighbors, including with smaller nations in Southeast Asia.

China’s rivalry with Japan is also fueled by resentment over imperial Japan’s occupation of parts of China in the first half of the 20th century and wartime abuses.

Sasae alluded to those concerns in his remarks at the Center for Strategic and International Studies.

“We have to always remember the history and past, but it’s not productive to only talk about the history and past things, and remembering and agitating the people’s emotions in a negative way. And that’s what I want to avoid,” Sasae said. “So I really hope that this year we could go into a very constructive dialogue with China.”

The immediate prospects aren’t rosy.

Japan’s Prime Minister Shinzo Abe visited a controversial war shrine in Tokyo in late December, angering China and even drawing U.S. disapproval. Among the 2.5 million war dead commemorated at the shrine are 14 war criminals from World War II.